Microwave electron discharge tubes



Jan. 20, 1959 G. PAPP 2,870,374

MICROWAVE ELECTRON DISCHARGE TUBES Filed May 26, 1954 4 Sheets-Sheet 1INVENTOR.

G EORGE PAPP ATTORNEY Jan. 20, 1

G. PAPP MICROWAVE ELECTRON DISCHARGE TUBES Filed May 26, 1954 4Sheets-Sheet 2 52 47 B4 5 mfimmfggmgw 49\ m mtggmgm 4 l \1 3 Bl ism wis: BS! m u in m w m s: in m 2 ha m a: (Q m a: m m m m INVENTOR. GEORGEPAPP ATTORNEY Jan. 20, 1959 G. PAPP 2,870,374

MICROWAVE ELECTRON DISCHARGE TUBES Filed May 26, 1954 4 Sheets-Sheet 5B4 W 5 Z Z Z: Y/i/ZZW/ B3 E 2 Z Z :W 6

is: P in I: a w w m m I: w

IN VEN TOR. GEQRGE PA PP ATTORNEY Jan. 20, 1959 G. PAPP 2,870,374

MICROWAVE ELECTRON DISCHARGE TUBES Filed May 26, 1954 4 Sheets-Sheet 4 Il I T I I I I p EQUTPUT II I IIIII I IOUTUT 8CHANNEL| I I I I I I I WAVEz 5 22: u 22 m 2% i l Immi Z2 22 z? lk21| QIZIIEZ 22 In I22 T22: 22 :21I

I l I l 2 l I I I HI I I B s: a: :3 :3 E3 it b'# a: s: I? FSII RI: n a:m ESI as ES 5:: j \NPUT DIRECTION OF: I I I I I I I l CHANNEL INPUT WAVEI I I I I I I l I 6 A IL I I/ I V IA] AI I 5 L dx x2 x2+dx x I E I xI+dxI D: I 5 IDIRECTION OF INPUT WAVE PROPAGATION FIG] INVENTOR. GEORGE PAPPATTORNEY MICROWAVE ELECTRON DISCHARGE TUBES George Papp, Fort Wayne,Ind.', assignor to lnternationai Telephone and Telegraph CorporationApplication May 26', 1954, Serial No. 432.57%

11 Claims. (Cl. 315-39) The present invention relates to extremely highfrequency electron discharge-devices, commonly characterized asmicrowave electron discharge tubes.

Numerous electron discharge devices have heretofore been devised forgenerating and utilizing high and ultrahigh frequencies. In the designand fabrication of these devices, the time of travel of the electrons asthey move from the cathode to the anode, commonly referred to as thetransit time, as well as the effect of inter-electrode capacities,constitute limitations in generating and handling appreciable quantitiesof power. Electron transit time, in certain known electron dischargedevices, serves to determine exactly the physicalspacing between thevarious electrodes, such spacing being in the order of fractions of amillimeter for the microwave frequencies with which this invention isconcerned. it has been found also that the shunting effect of theinter-electrode capacities limitsthe operating frequency range as wellas use of known techniques for modulating the electron current flowingfrom cathode to anode. Other limiting factors in the design of microwavetubes are well known to the art.

Recognizing, therefore, that serious limitations now obtain in the art,the present inventionicomprehends the utilization of the wavepropagation limitations in an electron discharge device for producingand handling greater quantities of power than has heretofore beenpossible in the microwave frequency range.

It is therefore an object of this invention to provide an electrondischarge device which may be used in the microwave frequency range toeither generateor amplify signals of relatively high power.

It is another object of this invention to provide a microwave dischargedevice which utilizes the effects of electron discharge current flowingfrom the cathode to the anode to "generate a multiplicity of incrementalsignals which may be collected in phase to amplify a given input signal.7

It is yet another object of this invention to provide an electrondischarge device capable of amplifying microwave frequency signals.

It is still another object of'this invention to provide anclectrondischarge device for use in the microwave range of frequencies,which is not limited in operation by discontinuities such as lumped tubeconstants or capacitive circuit losses.

Other objects will become apparent as the description proceeds.

In accordance with the present invention there is provided a high vacuumelectron discharge comprising an anode member ofv conducting material. Acathode or electron-emissive member is mounted in parallel spacedrelation with the anode'member and is separated therefrom by at leastone grid-like electrode also made of conductive material. Means areemployed for modul'an ing the flow of electrons from the cathode to theanode. In this arrangement, the grid-like element is spaced from Statesatent ice the anode member a distance dependent upon the electrontransit time, which-distance is preferably equal to one-half of theproduct of the period (in seconds) of the input high frequency signaltimes the velocity of the electrons impinging on the anode member (incentimeters per second). The cathode clement extends in thedirection ofthe input signal wave propagation while the electron stream flowstransversely to such direction. An output section extends also in thedirection of the input signal wave propagation with the mea'ns formodulating the stream being interposed between the anode and cathode.

For a better understanding of this invention, reference is made to thefollowing description, taken in connection with theacCOmpanyingdrawings, and its scope will be pointed out in theappended claims.

In the accompanyingdrawings: V

Fig. 1 is an axial section-in diagram form of one embodiment of thisinvention;

Fig. 2 is-an' axial section of another embodiment;

Fig. 3 is a partial axial'section similar to Fig. 1 showing stillanother embodiment of this'invention;

Fig. 4 is an enlarged fragmental section of the embodiment of-Fig. 3; I

Fig. 5 is a partial sectional view of yet another embodiment of thisinvention;

Fig. 6 is a partial section of a further embodiment similar to the oneof Fig. 5;-

Fig. 7 is a graph used in explaining the operation of this invention;and

Fig. 8 is another embodiment shown in longitudinal section which issimilar to Fig. 2.

With reference to Fig. 1, an evacuated electron discharge deviceof'cyl'indrical form is comprised of a straight elongated cathode 1which extends in the direction of input signal wave propagation, aninput grid 2 surrounding the cathode 1, an accelerating grid 3 radiallyspaced from the grid 2, and an anode 4 coaxially supported about thegrid 3. These various tube electrodes are maintained in rigid radialrelation by means of suitable annular glass or the like spacers, spacers5 and 5a separating the cathode from the input grid 2, spacers 6 and 6aseparating the two grids, and spacers 7 and 7a separating the grid 3from the anode 4.

The grids -2'and 3 may be composed of ordinary conductive screen orreticulate sheeting formed to a suit able tubular shape, the exactcomposition of these grids not being critical except for thefactthatthey be con structed of conductive material and be provided withopenings in radial registry through which electrons may flow from thecathode to the anode.

In the arrangement of Pig. l, the electron discharge device is containedessentially between the axially spaced arrangement of spacers 5, 561; 6,6a; and 7, 7a; however, in order to obtain optimum operatingcharacteristics, each of the aforedescribed tube elements-areextend'edaxially in opposite directions.

T he opposite extensions of the anode are indicated by the referencenumerals 9 and 9a respectively,.the corresponding extensions of the grid3 by the reference numerals 10 and 10a, the extensions ofthe grid 2 bynumerals 11 and 12, respectively, and the extensions of the cathode l'bythe reference numerals l3 and 14, respectively. All of these extensionsare'rnade of conductive material and may comprise sections of suitablemetal tubing. As will be explained more fully herewith, theextensions'll and'13' constitute theouter and inner conductors,respectively, of a coaxial signal input line of conventional design."

The cathode 1 grid '3, and anode 4'are conductively connected totheirrespective extensions; however, the

gamete grid 2 is capacitively coupled to its extensions ill and 12 bymeans of conventional stepped diameter concentric line chokes l5 and 16preferably made a quarter of a wave length long and surrounding therespective ends of the extensions 11 and 12. These high frequency chokesare Well known to the art and serve as conductors of microwave signalsand as open circuits to the pas sage of direct current.

The grid 3 and anode actually serve as the inner and outer conductors ofa coaxial line or signal output channel B. The extensions 9 and 10 atthe input side of the tube may be terminated in the usual manner by aresistor or resistor annulus a having a value equal to thecharacteristic impedance of the line. The righthand or signal output endof this line, generally indicated by the reference numeral 16a, is openfor utilization of the output signal.

The right-hand end of the coaxial line 12, ltd (channel A) is similarlyterminated by a resistor 37, preferably of annular shape, having aresistance equal to the characteristic impedance of that line.

The cylindrical space within the end partitions 5, 6, 7, and 5a, 6a, 70,respectively, and the anode 4 is evacuated in a manner well known to theart.

The cathode It is thermionically emissive and may be composed of any ofthe well known materials suitable for use in heated cathodes. In thepresent instance, the cathode is tubular and interiorly receives afilament 13 having leads 19 and 20 which are passed through the cathodewall 13 and brought out of the assembly by means of a conventionalshorted quarter-wave line 21 suitably connected into the input line 11,13. The opposite ends of the cathode are hermetically sealed by means ofthe two insulating plugs 22 and 23 for evacuating the space occupied bythe filament. Other methods of bringing the filament leads 19 and 20 outof the assembly, which do not disturb the operating characteristics ofthe tube, will occur to persons skilled in the art.

Operating potentials are supplied by the two batteries 24 and 25 of 400volts and volts, for example, respectively. The two batteries areconnected in series with the positive terminal of battery 24 leading tothe anode 4 and the negative terminal to the grid 2. The

negative terminal of the battery 25 is connected to the extension 11 tosupply negative voltage to the cathode, the conductive connection beingprovided by the shorted quarter-wave line 211.

In operation, electrons emitted by the cathode 1 will flow through thegrids 2 and 3 and be collected by the anode 4 thereby providing a spacedischarge current which may be detected in the external circuitry of thetube by any suitable means.

In further describing this invention, it is convenient to consider thetube assembly as comprising two coaxial lines, the line comprised of theouter conductor 2 and the inner conductor 1 serving as the signal inputline, referred to also as Channel A, and the line comprised of the innerconductor 3 and the outer conductor t constituting the output line,Channel B. in the complete assembly illustrated, the input line 1, 2includes the extensions 13, 14 and 11, 12 respectively so that a signalapplied to the coaxial extensions 11 and 13 will be conducted throughthe tube and be absorbed by the terminating resistor 17.

As the input signal is fed to the input line 11, 13, an electric field,modulated in accordance with the signal. is set up between the cathodeand grid 2, which field modulates the electron flow, and since thisfield varies progressively along the length of the line, such electronflow will be correspondingly affected along the tube length.

The tube may be of considerable length in comparison with the wavelength of the operating frequency. The input signal proceeds as a wavethrough the tube and 5 so modulates every axially successive incrementalsection of the tube. Every such section of the tube may therefore beregarded as a separate amplifier tube and may be designed to produceoptimum amplification which may be less than unity.

Since every axial section is excited in successive order, the generatedsignals leave the respective axial sections in the same order, each ofthese signals propagating down the line independently of each other. Aswill be explained more fully hereinafter, the incremental, generatedsignals are all eventually collected in the same phase for producing anamplified signal.

The potential on the grid 3 and anode 4 being much higher than thatcoupled to the input grid 2., electron flow will be directed andaccelerated toward the grid 3 and the anode 4. Since the potentialdifference between the grid 3 and anode 4 is zero, the velocity of theelectrons flowing in the radial space between the grid 3 and anode 4will be substantially uniform.

From this explanation it will be seen that at any in stant of time, at aselected axial position in the tube, the intensity of the electroncurrent flowing from the cathode will bear a value corresponding to theintensity of the modulating electric field between the con ductors 1 and2. The electron current will be oscillating with the frequency of themicrowave signal, and since it proceeds toward the anode, it will have awave like configuration in radial direction of a wave length equal tothe distance which an electron travels during one period of the signalinput. This electron Wave length may be expressed in the followingterms: We=Tv, where T equals the period in seconds of the input signal,and v equals the velocity of the electrons in centimeters per second.The distance between the cathode and anode corresponds to a number ofelectron wave lengths, and the spacing between the grid 3 and anode 4may be of plural wave lengths, but is preferably designed equal to ahalf wave length.

A typical wave instantaneously occurring between the cathode and anodeis represented by the wave form 26 in Fig. 1 which may be considered asoccurring in a cross-sectional plane at the selected axial point in thetube.

The signal induced in the output channel between elements 3 and 4 by thecross-sectional electron beam will propagate along the channel inopposite directions. It may be shown that the components generated indifferent cross sections of the tube travelling toward the output endare all in phase and additive while those directed toward the left areout of phase and consequently their sum is of a negligible magnitude.Leftward components from the axial points of contribution spaced aquarter wave-length apart cancel each other, consequently there will beno leftward wave in a tube of a multiple of half wave lengths long.

Thus, if the incremental currents induced in the coaxial line 3, 4 arecollected at the end of the tube let, the resultant total current willhave a relatively high value, and when this current is multiplied by thecharacteristic impedance of the transmission line 3, 4, it is seen thata signal voltage having a value many times that of an input signalvoltage is produced, and this amplified signal voltage may be coupledfrom the coaxial line 3, 4 by any suitable utilizing means well known tothe art.

Keeping the foregoing explanation in mind, and making particularreference to Fig. 7, the long tube may be regarded as being comprised ofa continuous succession of short tubes indicated in the figure by thedashed radial lines spaced a distance dx apart. The input signal waveproceeding along the input channel A may be represented by the formulawhere E (2. 1), is the high frequency electricfield intensity at point Xat instant t,

E is the amplitude of the field intensity,

Mam

where f is the frequency and tion will be d 1 am sin [w( t?) +5] where 1is thearnplitude of the total current, i. e.,

the sum of the convection and the displacement currents in a onecentimeter-long section of the tube. It can be shown, that 1 can beexpressed in the form i 1,=a sin We at "W? Where i is thecorrespondingamplitude of'the electron (convection) current; d is the distancebetween electrodes 3 and 4, and

We is the electron wave length, We=T.v defined above;

S is a phase constant being dependent upon operating conditions, beingthe same however at every section of the tube.

This current d1 generates a signal voltage where Z is thecharacteristicimpedance of the line 3, 4. This signal induced in channel B willpropagate as an electric wave, half of the signal travelling toward theright (+X direction) and the other half travelling left I (in the -Xdirection).

The wave component in the +X direction will have the form dV =Adx sin t-+s] where y is the distance travelled in channel B, which at point X isand

0 is the wave velocity in channel B.

The effect producing the signal in the tube length between at, and (x+dx) as derived in the foregoing, may

now be envisaged as occurring in every incremental tube length, e. g.,between x and (x +dx). Here the wave dV =Adx sin t-- +51 will begenerated, where s= 2 I All of these. elementary signals dVwillpropagate independently of eachother since the transmission there ofis a linear function.

6 If the tube design is such as to produce equal wave velocity in bothchannels A'and B, i. e., c =c =c., which is satisfied e. g.automatically by the TEM mode of transmission, the phase of all signalcomponents dV at point X willbe independent of the place of the signalgeneration x x etc.

Therefore, at the output end of the tube, X=L all ofthe'signalco-ntributions will arrive in the same phase adding to asummated value From the foregoing it will beseen thatthe incrementalgenerated signals dV of the respective sections dx may be of smallmagnitude but V can be appreciably greater than the input signal bymaking the tube sufliciently long.

Insofar as the leftwardsignal components Ada: sin w( t--' )+S areconcerned each will arrive at a selected point X in aphase dependentuponthe generating position x so that the sum of'the incremental signalsEdV will always be limited to a negligibly small value. The summationwill equal zero at the left or input end if the tube is an' integralnumber of half wavelengths long. In this case the left end of channel Bmay be terminated by a short circuit or left open as desired withoutaffecting the operation of the tube. Generally, however, a terminationby means of a resistance 15a will serve the best because no signalreflection will occur at any frequency.

From the foregoing explanation, for optimum results as is well known thespacing between'the grid 3 and anode 4 should equal one half theelectron wave length.

In'considering further embodiments of this invention, and forconvenientreference purposes, the embodiment of- Fig. 1 may be characterized as anon-resonant tube. The second embodiment of this invention is shown inFig. 2,.and in contrast to the former may be regarded as a resonanttube. This tube is very similar in construction to the tube ofFig. 1, inwhich case like numer alswill represent like parts.

Sincein order to obtain a relatively high degree of amplification in thetube of Fig. 1, it is necessary that this tube be of considerablelength, the amplification factor. being directly proportional to thetube length. However it becomes of practical importance to reduce thelength of the tube and yet obtain a given useful factor ofamplification. The'overall length of the tube of Fig. 2 is :made equalto a small integral number of half wavelengths of the operatingfrequency. The spacers 5, 6 and 7 at the left end and the spacers 5a, 6aand 7a on the right end are spaced inwardly from the respective ends adistance approximately equal to a half Wavelength of the operatingfrequency to locate them at volt age node points. The leftendofthe-coaxial line constituted by the inner-andouter conductors 3 and4, respectively, is terminated by" means of an annular shorting dis'k27. Similarly, the left endofthe coaxial line 11, .13, is terminated bya shortingdisk 28. An annular terminating disk 30 is conductivelyaffixed to the tight ends of the conductors 9a and Illa for terminatingthe line 3, 4 while a similar disk 35 terminates the right-hand end ofline 12, 14. A signal input connection is made to the line representedby the reference numerals 12 and 14 by means of the coaxial connector 31having an inner conductor which terminates in a loop 32 suitablyconductively secured to the inner periphery of the outer line conductor12. A similar coaxial connection 33 is coupled to the coaxial line 3, 4and is comprised of an inner condoctor also terminated by the loop 34secured to the conductor 4 as shown.

The signal input circuit for this tube is the coaxial line representedby the inner and outer conductors l4 and 12, respectively. This inputline is terminated on the right end by means of an annular disk 35 at alocation which will produce the desired resonant effect to be explainedmore fully hereinafter. As in the embodiment of Fig. l, the cathode 1 isthermionically emissive and is provided with a suitable heating filamentinteriorly thereof having loads 36 and 37 projecting from the right endof the hoilow cathode extension 14 as shown.

A source of operating potential, indicated as the battery 33, whichprovides, for example, a potential of 400 volts, its positive terminalconnected to the terminating d. (it for supplying the same positivepotential to the grid 3 and anode 4, and its negative terminal connectedto the shorting disk 35 for providing a direct current connection to thecathode i. The input grid 2 has a connection 39 leading to a terminal onthe battery 38 which supplies, for example, 30 volts of positivepolarity.

As explained previously, the overall length of the tube and itsextensions is made equal to an integral number of half wavelengths ofthe tube operating frequency. This being true, the wave of the signalintroduced by means of the connector 31 and lead 32 to the tube inputchannel between the conductors 12 and 14 and cathode It and grid 2 willtravel from right to left through this channel until it is reflected bythe terminating disk 28. By making the distance between the terminatingdisks 28 and 35 equal to an integral number of half wavelengths,standing waves will be produced in this input channel. This input linebeing resonant, the input signal will build up by using the proper inputconnection to a value limited only by the electrical attenuation andabsorption characteristic of the coaxial line itself. The ultimateamplitude of this resonant signal, will, of course,

be many times greater than the amplitude of the input signal introducedat the ri ht end by the connector 31.

The intense modulating field now set up between the cathode 1 and grid2, increases the intensity of the modulated part of the electron currentfor a given axial section of tube over that which was obtained in thecase of the tube of Fig. i. As in the case of Fig. l, incrementalsignals will be induced in the channel B and will add in phase toproduce an amplified wave which travels down the channel between thegrid 3 and anode 4 until it is reflected by the terminating disk 27 likethe input signal at the terminating disk 28. The phase relationship ofthe signals in channels B and A, respectively, after the efl ction, isthe same as it was previous to the reflection, so the amplification ofthe generated signal V in channel B will increase further as it would ina 11-- long tube which does not utilize reflection. The same has to besaid of the reflections at the terminating disks 39 and 35 it they areproperly positioned, the distance between the respective terminatingdisks (27, 30) and (28, 35) being an inte ral number of half Wavelengthsat the operating frequency.

From the description, it is evident that this resonant tube isequivalent in its operation to an infinitely long amplifier tube, havingthe advantage of increased current modulation and consequently increasedsignal gena'e rda ni 8: oration in the elementary sections of the tubeas was described above.

From the foregoing it will be seen that the resonant tube of Fig. 2 maybe of much shorter length than the tube of Fig. l for a given factor ofamplification.

Another embodiment of this invention which utilizes the principles ofthe foregoing is illustrated in Figs. 3 and 4. The principal differencein construction between this embodiment and the one of Fig. 2 resides inthe fact that this embodiment does not utilize reflected or standingwaves to produce a high initial modulation of the electron current inthe region of the cathode 1 and the grid 2, but instead employs theconcept of providing a multiplicity of coaxial output channels, such asthe one contained between the grid 3 and the anode 4. The signals of allof the output channels are added in phase to obtain an amplified signal.In this embodiment, like numerals will again indicate like parts.

As in the first-described embodiment, this tube may be severalwavelengths long at the tube operating frequency, and comprises thebasic coaxial electrodes ll, 2 and 3 which serve the same purpose andfunction in substantially the same manner as in the tube of Fig. 1.

Coaxially arranged with respect to the electrodes ll, 2 and 3 are aplurality of radially outwardly spaced grid electrodes bearing thereference numerals 45, 46 and 47, respectively, which define signalchannels B1, B2, B3 and 54, respectively.

An anode 4 coaxially surrounds these latter mentioned electrodes. All ofthese electrodes are preferably rigid or self-supporting in constructionand are maintained in their separated relationship by means of glass orthe like spacers of the type described in connection with the precedingembodiments. On the left end of this tube assembiy, the spacers mayconsist of annular resistance elements 48, 49, 5t, and 51 which areinterposed between the electrodes 3, 45, 46, 47, and 4, respectively.The values of these respective resistances are made equal to thecharacteristic impedances of the respective transmission lines embracingthe spacers, an example of this being that the spacer 43 has aresistance value equal to the characteristic of impedance of the coaxialline 3, 45. Each of the electrodes 45, 46, and 47 is made of a suitableconducting material having crosssectional thickness which makes itself-supporting, the tubular member comprising this material beingprovided with a multiplicity of radial openings or perforations 52 allarranged in radial registry. The electrons emitted by the cathode 1,will, therefore, find a radial path to the anode through these variousopenings 52.

The right-hand ends of the electrodes 45, 46 and t7 are tapered in crosssection as at 53 for a purpose which will become apparent hereinafter.As seen more clearly in Fig. 4, the respective adjacent electrodes 45,as and :7 are made such that the outer peripheries of the adjacentelectrodes will be spaced apart a. distance equal to one electron wavelength. This spacing is represented by the letter D.

For purposes of convenient explanation, this tube of Fig. 3 may beconsidered as comprising a multiplicity of the tubes of Fig. l. Theannular space between the grid 3 and anode 4 of Fig. 1 characterized asoutput channel B, corresponds to the annular space between the grid 3and electrode 45 of Fig. 3, denominated channel Bi. Similarly, thespaces between succeeding electrodes may be considered as constitutingadditional chan nels B2, B3, and as. In each one of these channels asignal is produced in exact phase conformity with the signals producedin the remaining channels, whereby all of the signals may be collectedin additive relation.

With reference to Fig. 4, a microwave signal fed to the input sectionll, 2 of the tube, will produce a flow of electron current to the anode,via the openings 52, which may be characterized by the Waveform 54 (Fig.4). From the application of this waveform 5%, to the tube geometry, agraphic illustration of the phase relation. of the electroncurrenttraversing the respective channels between the electrodes 3, 45,46, 47, and 4 is obtained. It will be noted that exact phase conformityprevails in these channels so that the individual electric fieldsproduced will, at any axial location in the tube,,be directed in acommon direction. Like the spacing of the electrodes 3, 45, 46, 47, 4 isprescribed to give exactly the same phase relationship in the channelsbetween them, the thickness of these electrodes are selected to giveoptimum signal generation in each of the channels. The resultant signalsproceeding down the respective channels B1, B2, B3 and B4 are at anygiven instant, radially of the tube, in exact phase relation, and sincethey travel toward the right emanate from the flaring mouth-provided bythe tapered end sections 53, a signal will be accumulated in the annularspace 59 contained between the right-hand ends of the grid 3 and theanode 4 which will have a value equal to the sum of the values of' theindividual output signals. The anode 4 and grid 3 may now be consideredas a coaxial transmission linefor coupling the amplified signal to asuitable load.

As will now be obvious, any number of electrodes or channels may beutilized to obtain an amplified signal, and

the tube may be made to any suitable length. Theoretically, the morechannels used or the longer the tube is made, the higher will be thegain factor of the tube.

By use of the multiple channels or zones of this embodiment shown inFig. 3, the same magnitude of output signal as produced by theembodiment of Fig. 1 of given length may be obtained by a tube ofshorter length.

A possible modification as shown in Fig. 5, of the embodiment of Figs. 3and 4, resides in fabricating each of the various electrodes 45, 46, and47 of two cylinders 45a and 45b, 46a and 46b and 47a and 47b,respectively, of spaced apart screen material. In this construction, inaddition to channels B1, B2, B3 and-B4 formed between electrodes 3 and45a, 45b and 46a, 46b and 47a, and 47b and 4, respectively, whichcorrespond in every respect to the channels of Fig. 3 which bear thesame reference symbols, additional channels B1, B2 and B3 are providedas shown.

Electrons (represented graphically by wave 54a) passing through theopenings of the grids generate waves travelling toward the right withincreasing amplitude in all of these channels. The waves in B1, B2, B3and B4, as in the case of Fig. 3, will be in exact phase, and in thechannels B1, B2 and B3 willbe in opposite phase conformity.

By closing channels B1, B2 and B3 with annular metal rings 55, 56 and57, which are extended by the tapered metal segments 53, the wavesgenerated in channels B1, B2, B3 and B4 can be collected in the line 59,between cylinders 3 and 4 exactly as described in connection with Fig.3. The waves generated in channels B1, B2 B3 and arriving at theshorting disks 55, 56, 57 respectively, will be reflected, and willpropagate leftward throug'n'the tube. If at the left end, channels Bil,B2, B3 and B4 are shorted by the tapered annular metal disks 65, 66, 67and 68 and amplified signal can be produced in the same manner in theleft end of the tube in cavity 59a, formed between electrodes 3 and 4.

Fig. 6 illustrates a still further embodiment of the invention. It isbuilt similar to the tube of Fig. 5, except that channels B1, B2, and B3are notshorted at the right end. Instead dielectric cylinders 75, 76, 77are inserted in these channels, which diminish the propagation velocityof the waves in the plugged portions of the respective channels. If thelengths of these plugs 75, 76, 77 are properly selected, so that thetravel time of the wave is lengthenedby one half period, the waves ofall the channels, as they enter the cavity 69, will be in additivephase. I

The phase shifting rings 75, 76 and 77 may be fabripated of any suitabledielectric material and to any suitable dimension which will provide thedesired phase transformation for bringing the wave generated in all ofthe channels into proper phase relationship. A graphic representation ofwhat happens in the various channels is indicated in the figure by atrain of sine waves in the respective channels. It will readily beappreciated that by shifting the phase of the intermediate channels,practically the entire radial space of the tube is utilized forgenerating the amplified signal. This feature enables the shortening ofthe tube for a given value of amplified signal in comparison with thetube shown in Fig. 3.

While all of the foregoing embodiments have been described in connectionwith amplification of a microwave signal, it will be readily understoodby a person skilled in the art that each of these embodiments may bemodified slightly to achieve sustained oscillation thereby providingmicrowave oscillators. This is accomplished, as shown in Fig. 8, byfeeding a small quantity of the amplified signal back into the inputchannel between the cathode and the adjacent grid 2. A suitable coaxialline 78 or cavity connection interconnecting the input and outputchannels of the respective tubes may be utilized for feeding a signalfrom the output channel to the input channel for achieving sustainedoscillations. It is understood as well that this connection between theoutput and input channels may be more closely coupled. Such is the case,for example, in reflex klystrons or in magnetrons, where the twochannels are the same. Following the motion of the electrons, it ispossible in the case of refiex klystrons to separate in time the twodifferent actions between the electron beam and this only channel, thesebeing the same actions as were attributed above to the channels A and B,while this distinction is not possible any more in the case ofmagnetrons.

In any event, regardless of Whether the general idea of this inventionis incorporated in a true amplifier or in an oscillator, the signalcontributionsof the various incremental sections of the tube arecollected in phase to produce the ultimate output signal.

While there has been described what, at present, is considered thepreferred embodiments of the invention, it will be obvious to thoseskilled inthe art that various changes and modifications may be madetherein without departing from the invention, andtherefore, it is aimedin the appended claims to cover all such-changes and modifications asfall within the true spirit and scope of the invention.

What is claimed is:

1. An electrondischarge device for use in the utilization of microwavefrequency signals comprising signal input and signal output channelsarranged respectively for signal propagation in the same direction, saidinput channel being constituted by an elongated coaxial line havinginner and outer conductors, the inner conductor serving as a cathode andemitting electrons throughout its length, the outer conductor beingradially perforated therethrough throughout its length, the outputchannel being'constituted by a second elongated coaxial line havinginner and outer conductors supported in spaced coaxial relation to thefirst-mentioned coaxial line, the inner conductor of said second linebeing radially perforated throughout its length to provide paths forelectron flow from said first line, the outer conductor of said secondline serving as an anode throughout its length so that the microwavesignal voltage applied to said input channel is propagated in said firstcoaxial line and modulates said electrons emitted from said cathode inevery axially successive incremental section thereof thereby providingaxially incremental signals in said second coaxial line which add inphase to provide an amplified signal in said output channel. 7

2. The device of claim lincluding means for electrically insulating theinput and output lines from each other, and a unidirectionalvoltagesource connected to impress the same relatively high positive potentialon said inner and outer conductors of said second coaxial line, arelatively lower positive potential on said outer conductor of saidfirst coaxial line, and the lowest potential on said inner conductor ofsaid first coaxial line.

3. The device of claim 1 in which the inner and outer conductors of saidsecond coaxial line are spaced apart by one half the electron wavelengthof said device.

4. The device of claim 1 in which the opposite ends of the coaxial linesare shorted respectively and said coaxial lines respectively havelengths which are an tegral number of half wavelengths of the signalfrequency so that said lines are respectively resonant at saidfrequency.

5. An electron discharge device for use in the utilization of microwavefrequency signals comprising: signal inp'. and signal output channelsarranged respectively for s nal propagation in the same direction, saidch being constituted by an elongated coa h vi' inner and outerconductors, with said inner conductor serving as a cathode, said outputchannel being constituted by a second elongated coaxial line havinginner and outer conductors disposed in spaced coaxial relation to saidinput line with said outer conductor serving as an anode, and meanscooperating with said input and output lines defining an axiallyextending evacuated electron discharge zone between said cathode andsaid anode, said outer conductor of said input line and said innerconductor of said output line being respectively radially perforatedthroughout their lengths and said cathode being arranged for electronemission throughout its length in said Zone whereby a microwave signalvoltage applied to said input channel is propagated in said firstcoaxial line and modulates said electrons emitted by said cathode inevery axially successive incremental section there-oi thereby providingaxially incremental signals in said second coaxial line which add inphase to provide an amplified signal in said output channel.

6. An electron discharge device for use in the utiliza tion of microwavefrequency signals comprising: signal input and output channels arrangedrespectively for signal propagation in the same direction. said inputchannel being constituted by an elongated coaxial line having inner andouter conductors with said inner conductor serving as a cathode, saidoutput channel being constituted by a second elongated coaxial line andhaving inner and outer conductors disposed in spaced coaxial relation tosaid in ut line with said outer conductor serving as an anode, firstspacing means for radially spacing and supporting said input and outputline conductors, and second spacing means for radially spacing andsupporting said input and output line conductors and axially spaced fromsaid first spacing means to define an evacuated electron discharge Zonetherewith between said cathode and said anode, said outer conductor ofsaid input line and said inner conductor of said output line beingrespectively radially porforated throughout their lengths in said zone,said cathode being arranged for electron emission throu hout its lengthin said zone and the inner and outer conductors of said second coaxialline being spaced apart by onehalt the electron wavelength of saiddevice whereby a microwave signal voltage applied to said in ut channelis propagated in said first coaxial line and modulates said electronsemitted from said cathode and every axially successive incrementalsection thereof thereby providing axially incremental signals in saidsecond coaxial l e which add in phase to provide an amplified signal insa d output channel.

7. The device of claim 6 in which the opposite ends of said input andout ut lines are res ectively shorted and said input and output linesextendin a distance of approximately one-half the Wavelength of the sigl frequency respectively beyond said first and second 5 cing means andrespectively having over-all lengths which are an integral number ofone-half wavelengths of the signal frequency so that said input andoutput lines are respectively resonant at said frequency.

attain A I Lei 8. An electron discharge device for use in theutilization of microwave frequency signals comprising an input signalchannel constituted by an elongated length of coaxial line having innerand outer conductors, the inner conductor serving as a cathode andemitting electrons throughout its length and the outer conductor havinga plurality of openings therethrough throughout its length to provide aplurality of radial paths for the flow of electrons therethrough, and aplurality of coaxial output signal channels coaxially surrounding saidinput channeI and being comprised of a plurality of radially spacedtubular electrodes which are all, with the exception of the outermostelectrode, provided with a plurality of radial openings throughout theirlengths for passing the aforementioned flow of electrons, saidelectrodes being radially spaced apart a distance which will place theouter peripheral surfaces of adjacent electrodes a full wave length ofelectron flow apart, said electrodes further providing coaxial channelsinteriorly thereof so that the microwave signal applied to said inputchannel is propagated in said first coaxial line and modulates saidelectrons emitted from said cathode in every axially successiveincremental section thereof thereby providing axially incrementalsignals in said output signal channels, the same respective ends of saidinterior channels being furnished with phase-shifting means whereby thesignals generated in all channels will adjust into additive phaserelation, the innermost and outermost of said electrodes serving as theinner and outer conductors respectively of an elongated output coaxialline and extendin axially beyond the ends of said phase-shifting meansto provide a collection cavity in which the signals produced by theindividual output channels may be added in phase to pro duce anamplified output signal in said cavity, said output coaxial line beingarranged to propagate the output signal in the same direction as thepropagation of the input signal in the input signal channel.

9. An electron discharge device for use in the 'lization of microwavefrequency signals comprising an input signal channel constituted by anelongated length of coaxial line having inner and outer conductors, theinner conductor serving as a cathode and emitting electrons throughoutits length and the outer conductor having a plurality of openingstherethrough throughout its length to provide a plurality of radialpaths for the flow of electrons therethrough. and a plurality ofradially spaced coaxial output signal channels coaxially surroundingsaid input channel and being comprised of a plurality of radially spacedtubular electrodes provided with a plurality of radial openingsthroughout their lengths for passing the aforementioned flow ofelectrons so that the microwave signal applied to said input channel ispropagated in said first coaxial line and modulates said elec onsemitted from said cathode in every axially success ncremental sectionthereof thereby providing axially incremental signals in said outputsignal channels, adjacent electrodes being radially spaced apart adistance which will serve to produce signals in all output channelswhich are in phase, the same ends of said output channels beingterminated by impedances having values equal to the characteristicimpedances of the respective output channels, the ends of said eectrodes remote from the last-mentioned impedances being tapered toprovide channel openings or" axially progressive width, the innermostand outermost oi said l-cctrcdes serving as the inner and outer cnductors repectively of an elongated output coaxial line and extend mgaxially beyond the ends of said tapered ends to provide a collectioncavity in which the signals produced by the individual output channelsmay be added in phase to produce an amplified output signal in said catisaid output coaxial line being arranged for propagation of said outputsignal in the same direction as the propagation of the input signal inthe input signal channel.

10. An electron discharge device for use in the utilization of microwavefrequency signals comprising an input signal channel constituted by anelongated length of coaxial line having inner and outer conductors, theinner conductor serving as a cathode and emitting electrons throughoutits length and the outer conductor having a plurality of openingstherethrough throughout its length to provide a plurality of radialpaths for the flow of electrons therethrough, and a plurality ofradially spaced coaxial output signal channels coaxially surroundingsaid input channel and being comprised of a plurality of radially spacedtubular electrodes provided with a plurality of radial openingsthroughout their lengths for passing the aforementioned flow ofelectrons so that the microwave signal applied to said input channel ispropagated in said first coaxial line and modulates said electronsemitted from said cathode in every axially successive incrementalsection thereof thereby providing axially incremental signals in saidoutput channels, said electrodes being radially spaced apart a distancewhich will place the outer peripheral surfaces of adjacent electrodes afull wavelength of electron fiow apart, adjacent electrodes beingradially spaced apart a distance which will serve to produce signal inall output channels which are in phase, the same ends of said outputchannels being terminated by annular shaped impedance members havingimpedance value corresponding to the characteristic impedance of therespective output channel, the opposite ends of said output channelsbeing open, the innermost and outermost of said electrodes serving asthe inner and outer conductors respectively of an elongated outputcoaxial line and extending axially beyond the open ends of said outputchannels to provide a collection cavity in which the signal produced bythe individual output channels may be added in phase to produce anamplified output signal in said cavity, and a coaxial connection coupledto the cavity conductors for conducting the amplified signal therefromand with propagation in the same direction as the propagation of theinput signal in said input channel.

11. An electron discharge device for use in the utilization of microwavefrequency signals comprising an input signal channel which extends inthe direction of signal propagation, said channel being defined by twoelongated spaced conductors, one of which being electron emissivethroughout its length and the other of which being pervious to thepassage of electron flow throughout its length, said electron flow beingtransverse to the direction of signal propagation, a plurality of outputchannels disposed in progressive spaced relation from said input channeland extending parallel to the direction of said signal propagation, saidoutput channels being separated by a plurality of conductive memberswhich are pervious to said electron flow throughout their lengths sothat the microwave signal applied to said input channel is propagated insaid first coaxial line and modulates said electrons emitted from saidcathode in every axially successive incremental section thereof therebyproviding axially incremental signals in said output channels, saidconductive members being spaced apart a distance which provides for thegeneration of a signal in each output channel in response to saidelectron flow thereacross whereby the generated signals in one series ofalternate channels are in exact phase relation and the generated signalsin the other series of alternate channels are in phase with each otherbut opposite to the signals of said one series of channels, first meansdisposed at the same ends of series of said alternate channels tofacilitate collection of all signals therefrom which are in phase, andsecond means disposed at the other ends of said other series ofalternate channels to facilitate collection of all signals therefromwhich are in phase.

References Cited in the file of this patent UNITED STATES PATENTS2,122,538 Potter July 5, 1938 2,128,231 Dallenbach Aug. 30, 19382,153,728 Southworth Apr. 11, 1939 2,368,03l Llewellyn Jan. 23, 19452,721,957 Neher Oct. 25, 1955 2,785,338 Goodard Mar. 12, 1957 FOREIGNPATENTS 125,174 Australia Aug. 12, 1947

